A sensor for detecting proteins or trace ingredients of physiologically active substances in organisms has a signal conversion element, namely a transducer, in addition to a molecular recognition element. The molecular recognition element detects chemical or physical reactions, and the signal conversion element converts detected signals into electrical signals to detect materials to be tested.
As one of such sensors, the one using a field-effect transistor (FET) as a signal conversion element is known, and a pH sensor, glucose sensor, etc. using an ion-sensitive field-effect transistor having an ion-selective membrane have been put to practical use. By using an FET as a signal conversion element, downsizing and integration of sensors can be achieved based on conventional semiconductor manufacturing technologies.
It has recently been desired to achieve a sensor that operates more quickly, simply, and sensitively compared to conventional reagents for antibody test, reagents for antigen test such as viruses, and equipment for the tests. For example, as disclosed in Patent Literatures 1 and 2, some biosensors using an FET as a signal conversion element have been proposed. Furthermore, sensors using a two-terminal element as a signal conversion element have also been proposed (Patent Literature 3).
The inventor et al. have proposed in Patent Literature 4 a sensor in simple and highly-flexible structure including a two-terminal signal conversion element and having high sensitivity comparable to that of the sensor integrating an FET as a signal conversion element.
However, only a few such sensors have been put to practical use as pH sensors or glucose sensors equipped with a signal conversion element. In other words, a sensor equipped with a molecular recognition element and a signal conversion element for detecting proteins or trace ingredients of biologically active substances in organisms has yet to be put to practical use.